Electrical insulating ring located between an end cap and a tension sleeve of an undersea pressure vessel housing an optical amplifier module

ABSTRACT

A pressure vessel is provided for use in an undersea environment. The pressure vessel including a pressure housing and at least two cable receiving elements disposed on opposing ends of the pressure housing for respectively receiving ends of optical cables that each include an electrical conductor therein, said cable receiving elements adapted to be in electrical contact with the respective electrical conductors in the optical cables. At least one optical amplifier is located in the pressure vessel. The optical amplifier includes at least one electrical component adapted to receive electrical power from the electrical conductors in the optical cables. The pressure vessel also includes an electrically insulating element electrically isolating at least one of the cable receiving elements from the pressure housing.

STATEMENT OF RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S. patentapplication Ser. No. 10/715,330, filed Nov. 17, 2003 and entitled“Method And Apparatus For Electrically Isolating An Optical AmplifierModule Housed In A Universal Cable Joint,” which is incorporated byreference in its entirety herein.

This application is also a continuation-in-part of co-pending U.S.patent application Ser. No. 10/800,424, filed Mar. 12, 2004 and entitled“Thermal Management Of An Optical Amplifier Module Housed In A UniversalCable Joint,” which is incorporated by reference in its entirety herein.

This application is also related to co-pending U.S. patent applicationSer. No. 10/687,547, filed Oct. 16, 2003 and entitled “Optical AmplifierModule Housed In A Universal Cable Joint For An Undersea OpticalTransmission System, which is incorporated by reference in its entiretyherein.

FIELD OF THE INVENTION

The present invention relates to the field of optical repeaters, andmore particularly to an optical repeater employed in an undersea opticaltransmission system.

BACKGROUND OF THE INVENTION

In undersea optical transmission systems optical signals that aretransmitted through an optical fiber cable become attenuated over thelength of the cable, which may span thousands of miles. To compensatefor this signal attenuation, optical repeaters are strategicallypositioned along the length of the cable.

In a typical optical repeater, the optical fiber cable carrying theoptical signal enters the repeater and is coupled through at least oneamplifier and various components, such as optical couplers anddecouplers, before exiting the repeater. These optical components arecoupled to one another via optical fibers. Repeaters are housed in asealed structure that protects the repeaters from environmental damage.During the process of deployment, the optical fiber cable is coiled ontolarge drums located on a ship. Consequently, the repeaters becomewrapped about the drums along with the cable. Due to the nature of thesignals, and the ever increasing amount of information being transmittedin the optical fibers, repeaters are getting larger, and their increasedlength creates problems as they are coiled around a drum. Although thedrums may be up to 9-12 feet in diameter, current repeaters may begreater than 5 feet in length, and, therefore, are not able to lie flat,or even substantially flat, along a drum. Tremendous stresses due toforces on the order of up to 100,000 pounds are encountered at theconnection point between the repeater and the fiber optic cable to whichit is attached, especially during paying out and reeling in of thecable. The non equi-axial loading across the cable may arise as a resultof severe local bending that is imposed on the cable at its terminationwith the repeater. This loading would inevitably lead to failure ofcable components at loads well below the tensile strength of the cableitself.

To prevent failure of the cable during deployment of the repeater, abend limiter is often provided, whose purpose is to equalize the forcesimposed on the cable. In addition, a gimbal may be provided at eachlongitudinal end of the repeater to which the bend limiting devices areattached. The gimbal provides free angular movement in two directions.The bend angle allowed by the gimbal between the repeater and bendlimiting device further reduces the local bending that is imposed on theoptical fiber cables.

The large physical size of conventional repeaters increases theircomplexity and cost while creating difficulties in their deployment.

SUMMARY OF THE INVENTION

In accordance with the present invention, a pressure vessel is providedfor use in an undersea environment. The pressure vessel including apressure housing and at least two cable receiving elements disposed onopposing ends of the pressure housing for respectively receiving ends ofoptical cables that each include an electrical conductor therein, saidcable receiving elements adapted to be in electrical contact with therespective electrical conductors in the optical cables. At least oneoptical amplifier is located in the pressure vessel. The opticalamplifier includes at least one electrical component adapted to receiveelectrical power from the electrical conductors in the optical cables.The pressure vessel also includes an electrically insulating elementelectrically isolating at least one of the cable receiving elements fromthe pressure housing.

In accordance with one aspect of the invention, the electricallyinsulating element comprises a ceramic element.

In accordance with another aspect of the invention, the pressure housingand said electrically insulating element are cylindrical in shape andare equal in diameter.

In accordance with another aspect of the invention, the pressure housingis formed from a metallic material.

In accordance with another aspect of the invention, an optical amplifiermodule is provided that contains the optical amplifier. The moduleincludes an internal housing having an outer dimension substantiallyequal to an outer dimension of an internal fiber splice housing of anundersea optical fiber cable joint. The internal housing includes a pairof opposing end faces each having a retaining element for retaining theinternal housing within an outer housing of the undersea optical fibercable joint. The internal housing also includes a sidewallinterconnecting the opposing end faces, which extends between theopposing end faces in a longitudinal direction. The sidewall, which isformed from a thermally conductive material, includes a receptacleportion having a plurality of thru-holes each being sized to receive apassive optical component employed in an optical amplifier. The modulealso includes at least one circuit board on which reside electronicssuch as at least one voltage dropping element associated with theoptical amplifier.

In accordance with another aspect of the invention, at least one opticalpump source is in thermal contact with one of the end faces.

In accordance with another aspect of the invention, the end faces eachinclude at least one inwardly extending boss. The optical pump sourceresides on one of the inwardly extending bosses.

In accordance with another aspect of the invention, a first side of thecircuit board resides on a surface extending through the sidewall. Athermally conductive pad is mounted to the first side of the circuitboard and provides a thermally conductive path between the voltagedropping element and the sidewall.

In accordance with another aspect of the invention, the voltage droppingelement is mounted to the thermally conductive pad.

In accordance with another aspect of the invention, the voltage droppingelement is a zener diode.

In accordance with another aspect of the invention, the plurality ofthru-holes laterally extends through the receptacle portion of thesidewall in the longitudinal direction.

In accordance with another aspect of the invention, the internal housinghas a generally cylindrical shape. The receptacle portion of thesidewall has a curvature that defines a diameter of the cylindricalshape.

In accordance with another aspect of the invention, the undersea opticalfiber cable joint is a universal joint for jointing optical cableshaving different configurations.

In accordance with another aspect of the invention, the optical fiberstorage area includes at least one optical fiber spool around whichoptical fiber can be wound.

In accordance with another aspect of the invention, the internal housingis formed from a pair of half units that each include one of theretaining elements.

In accordance with another aspect of the invention, the sidewallincludes a pair of ribbed members extending longitudinally from thereceptacle portion of the sidewall. The ribbed members each have atension rod thru-hole extending laterally therethrough in thelongitudinal direction for supporting a tension rod employed by theundersea optical fiber cable joint.

In accordance with another aspect of the invention, the outer dimensionof the internal housing is less than about 15 cm×50 cm.

In accordance with another aspect of the invention, the outer dimensionof the internal housing is about 7.5 cm×15 cm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of an undersea optical fiber cable.

FIG. 2 shows a simplified schematic diagram of a universal cable jointfor jointing fiber optic cables for use in undersea opticaltelecommunication systems.

FIG. 3 shows a particular example of a universal cable joint that isavailable from Global Marine Systems Limited and the Universal JointConsortium.

FIG. 4 shows a side view of an optical amplifier module constructed inaccordance with the present invention.

FIG. 5 shows a perspective view of one of the half units that form theoptical amplifier module depicted in FIG. 4.

FIG. 6 shows a side view of one of the half units that form the opticalamplifier module depicted in FIG. 4.

FIG. 7 shows a cross-sectional side view one of the half units that formthe optical amplifier module depicted in FIG. 4.

FIG. 8 is cross-sectional side view of the optical amplifier moduleshown in FIG. 4.

FIG. 9 is an enlarged, cross-sectional side view of the portion of theoptical amplifier module that interconnects with the end cap.

FIG. 10 shows a plan view of the bottom of one of the circuit boardsillustrating the manner in which the zener diodes are mounted tofacilitate heat transfer.

FIG. 11 shows a perspective view of one embodiment of the pressurevessel that houses the optical amplifier module.

DETAILED DESCRIPTION

The present inventors have recognized that a substantially smallerrepeater can be achieved by first reducing the length of the repeater sothat the stresses placed upon it during its deployment are greatlyreduced, thereby eliminating the need for gimbals. The elimination ofthe gimbals, in turn, allows further reductions in the dimensions of therepeaters.

The present inventors have further recognized that a repeatersubstantially reduced in size can be housed in a unit formed fromoff-the-shelf components that have been qualified for the underseaenvironment. In particular, the inventors have recognized that a housingconventionally used for interconnecting different undersea optical fibercables can also be used as an ultra-small form-factor repeater housing.As discussed below, one such housing, commonly referred to as theUniversal Joint, has become the defacto worldwide standard formaintaining submarine cables and has a lengthy history of successfuldeployment. The present invention thus provides a repeater that, becauseof its small size, is easily deployed and which is located in aneconomical, submarine qualified housing that is already well establishedin the undersea optical communications industry. Moreover, because theUniversal Joint can interconnect different optical fiber cables, therepeater can be used to interface with a variety of cables and systemsfrom different manufacturers.

To facilitate an understanding of the present invention, an example ofan undersea optical fiber cable will be described in connection withFIG. 1. While different cable manufactures employ cables havingdifferent configurations and dimensions, most cables employ most of thecomponents depicted in FIG. 1 in one form or the other. Optical cable330 comprises a single, centrally located gel-filled buffer tube 332made from a metal such as aluminum or stainless steel. The gel-filledbuffer tube 332 contains optical fibers 335. In some cases the buffertube 332 is replaced with a centrally disposed kingwire that issurrounded by optical fibers that are embedded in a polymer. Two layersof strandwires, which serve as strength members, are wound around thebuffer tube. One layer includes strandwires 338 and the other layerincludes strandwires 339. A copper conductor 340 surrounds thestrandwires and serves as both an electrical conductor and a hermeticbarrier. An outer jacket 342 formed from polyethylene encapsulates thecopper conductor 340 and serves as an insulating layer.

FIG. 2 shows a simplified schematic diagram of a universal cable jointfor jointing fiber optic cables for use in undersea opticaltelecommunication systems. Such a joint is referred to as a universalcable joint because it can interconnect many different types of underseaoptical telecommunication cables, regardless of manufacturer. The cablejoint includes a common component assembly 10 in which an optical fibersplice is located. The fiber splice is formed from two fibers thatrespectively originate in two cables that each terminate in cabletermination units 12. A protective assembly 15 surrounds commoncomponent assembly 10 and cable termination units 12 to provideprotection from the external environment.

FIG. 3 shows a particular example of a universal cable joint that isavailable from Global Marine Systems Limited and the Universal JointConsortium, which, as previously mentioned, is often simply referred toas the Universal Joint. In FIGS. 2 and 3, as well as the figures thatfollow, like reference numerals indicate like elements. In FIG. 3, theprotective assembly 15 depicted in FIG. 2 comprises a stainless steelsleeve 14 that surrounds the common component assembly 10 and apolyethylene sleeve 16 that is molded over the common component assembly10. The stainless steel sleeve 14 provides resistance to tensile,torsional and compressive loads and further provides an electricallyconductive path through which electrical power can be transmitted fromthe copper conductor of one cable to the copper conductor of the other.

The jointing process begins by stripping back the various layers of thecable to reveal predetermined lengths of the outer jacket, copperconductor, strandwires, and the fiber package (e.g., the buffer tubecontaining the optical fibers or the kingwire surrounded by the opticalfibers). The strandwires are clamped in a ferrule assembly located inthe cable termination units 12. The fiber package extends into thecommon component assembly 10, where it is held in place by a series ofclamps. In the common component assembly 10 the individual fibers areseparated and spliced to their corresponding fibers from the othercable. The splices, along with excess fiber, are looped and wound inchannels that are formed within the common component assembly 10. Thecommon component assembly 10 is inserted in the stainless steel sleeve14 and end caps 13 are screwed to each end of the assembly 10. Twotension rods 17 and 19 extend through the end caps 13 and the commoncomponent assembly 10. The tension rods 17 and 19 are designed to carrythe tension loads that are placed on the universal joint during thedeployment process as the joint is transferred from a ship to itsundersea environment. Finally, the joint is laid in a mold that isinjected with molten polyethylene to provide an insulate (i.e.,polyethylene sleeve 16) that is continuous with the outer jacket of thecables. The assembly defined by the stainless steel sleeve 14 and theend caps 13 serves as a pressure vessel in which the cable joint ishoused.

The present inventors have recognized that a cable joint such as theuniversal cable joints depicted in FIGS. 2-3 can be modified to serve asa repeater housing in which 1 or more optical amplifiers are located.FIGS. 4-9 show one embodiment of an optical amplifier module 400 thatreplaces the common component assembly 10 seen in FIGS. 1-4. The opticalamplifier module 400 must have substantially the same dimensions as thecommon component assembly, which is only about 7.5 cm×15 cm. Aspreviously mentioned, this is far less in size than conventionalrepeater housings, which are often several feet in length. The opticalamplifier module 400 depicted in the figures can support 4 erbium-dopedfiber amplifiers (EDFAs), physically grouped as a dual amplifier unitfor each of two fiber pairs. Of course, the present inventionencompasses optical amplifier modules that can support any number EDFAs.

Each optical amplifier includes an erbium doped fiber, an optical pumpsource, an isolator and a gain flattening filter (GFF). The amplifiersare single-stage, forward pumped with cross-coupled pump lasers. A 3 dBcoupler allows both coils of erbium doped fiber in the dual amplifier tobe pumped if one of the two pump lasers fails. At the output, anisolator protects against backward-scattered light entering theamplifier. The gain flattening filter is designed to flatten theamplifier gain at the designed input power. An additional optical pathmay be provided to allow a filtered portion of the backscattered lightin either fiber to be coupled back into the opposite direction, allowingfor COTDR-type line-monitoring. Of course, optical amplifier module 400may support EDFAs having different configurations such as multistageamplifiers, forward and counter-pumped amplifiers, as well as fiberamplifiers that employ rare-earth elements other than erbium.

The optical amplifier module 400 is designed to be compatible with theremainder of the cable joint so that it connects to the cabletermination units 12 and fits within the stainless steel sleeve 14 inthe same manner as the common component assembly 10.

A side view of optical amplifier module 400 is shown in FIG. 4 with endcaps 13 in place. The module 400 is defined by a generally cylindricalstructure having flanges 402 (seen in FIG. 5) located on opposing endfaces 403. A longitudinal plane 405 extends through the opticalamplifier module 400 to thereby bisect the module 400 into two halfunits 404 and 404′ that are symmetric about a rotational axisperpendicular to the longitudinal plane 405. That is, as best seen inFIG. 5, rather than dividing the end faces 403 into two portions locatedon different half units 404, each half unit 404 includes the portion ofone of the end faces 403 on which a respective flange 402 is located.FIG. 5 shows a perspective view of one of the units 404. In theembodiment of the invention depicted in FIGS. 4-9, each half unit 404houses two erbium-doped fiber amplifiers

Flanges 402 mate with the cable termination units 12 of the UniversalJoint shown in FIG. 3. As seen in the cross-sectional views of FIGS. 7and 8, through-holes 407 extend inward from the end faces 403 throughwhich the tension rod of the universal joint are inserted. The end faces403 also include clearance holes 430 for securing the end caps 13 of theUniversal Joint to the optical amplifier module 400. The clearance holes430 are situated along a line perpendicular to the line connecting thetension rods thru-holes 407.

As shown in FIGS. 4-6, each unit 404 includes curved sidewalls 412forming a half cylinder that defines a portion of the cylindricalstructure. A spinal member 406 is integral with and tangent to thecurved sidewalls 412 and extends longitudinally therefrom. The thru hole407 containing the tension rod of the universal joint extends throughthe spinal member 406. A ceramic boss 440 is located on the end of thespinal member 406 remote from the end flange 403. As shown in FIGS. 5and 7, the thru hole 407 extends through the ceramic boss 440. Asdiscussed below, the ceramic boss 440 prevents the flow of current fromone half unit 404 to the other.

A circuit board support surface 416 extends along the periphery of theunit 404 in the longitudinal plane 405. Circuit board 426 is mounted onsupport surface 416. When the half units 404 and 404′ are assembled,circuit boards 426 and 426′ are interconnected by a pair of interlockingconductive power pins 423 that provide electrical connectivity betweenthe two circuit boards 426 and 426′. The inner cavity of the unit 404located between the circuit board support surface 416 and the spinalmember 406 serves as an optical fiber storage area. Optical fiber spools420 are located on the inner surface of the spinal member 406 in theoptical fiber storage area. The erbium doped fibers, as well as anyexcess fiber, are spooled around the optical fiber spools 420. Theoptical fiber spools 420 have outer diameters that are at least greatenough to prevent the fibers from bending beyond their minimum specifiedbending radius.

The curved sidewalls 412 are sufficiently thick to support a pluralityof thru-holes 418 that extend therethrough in the longitudinaldirection. The thru-holes 418 serve as receptacles for the passivecomponents of the optical amplifiers. That is, each receptacle 418 cancontain a component such as an isolator, gain flattening filter, couplerand the like.

End faces 403 each include a pair of pump support bosses 403 a (seeFIGS. 6 and 7) that extend inward and parallel to the circuit board 426.The circuit board 426 has cut-outs so that the pump support bosses 403 aare exposed. A pump source 427 that provides the pump energy for eachoptical amplifier is mounted on each pump boss 403 a.

Electrical Connectivity

As previously mentioned, electrical connectivity must be maintainedbetween the cables in the two cable termination units 12. However, thevarious components in the optical amplifier module 400 must beelectrically isolated to enable a small voltage (e.g., 5-20v) that mustbe supplied to the electrical components located on the circuit boards426.

Referring again to FIG. 3, the optical amplifier module 400 and sleeve14 are surrounded by polyethylene sleeve 16, which serves as adielectric. Electrical power is taken from the conductor in the cablelocated in the termination units 12 and transferred through a conductorlocated in the circuit board 426. The circuit board is electricallyisolated from the optical amplifier module 400, with the epoxy resin ofthe circuit board acting as a local dielectric. After the voltage isdropped to the electrical components on one of the circuit boards thevoltage is passed from circuit board 426 to circuit board 426′ via apair of complaint conductive pins 423 that each comprise a pin andsocket assembly. The pins 423 allow for any axial movement that mayoccur as a result of tension or hydrostatic pressure.

More specifically, with reference now to FIGS. 7 and 8, power issupplied to the electrical components as follows. Since the cabletermination units 12 are electrically powered or active, end caps 13 arealso electrically active. A power conductor extends within each of thecircuit boards 426 and 426′. The power conductors receive electricalpower directly from the pump support bosses 403 a. One or more voltagedropping elements such as zener diodes are located on the circuit board426. The zener diodes, which electrically couple the power conductors tothe other electrical components on the circuit board, drop a voltagethat is sufficient to power the electrical components. Electricconnectivity extends along the power conductors and is maintained acrossthe circuit boards to the other via the conductive pins 423. In this wayelectric conductivity extends from one end cap 13, through the endflange 403 and pump support boss 403 a in contact with the end cap 13,through the power conductor located on the circuit board 426 resting onthe pump support boss 403 a, through one of the power pins 423 andthrough the power conductor located in the other circuit board 426.Finally, electrical conductivity extends to the other end cap 13 via theother pump support boss 403 a and end flange 403.

The electrical path is isolated from the optical amplifier module 400 asfollows. An electrically insulating pad is located between the circuitboard support surface 416 and the circuit board 426. In this way thepump support boss 403 a is electrically isolated from the circuit board426, except through the aforementioned power conductor. Ceramicisolators 442 surround the bolts that secure the circuit board 426 tothe sidewalls 412 of each half unit 404. The ceramic isolators 442prevent electrical discharges from the bolts to the components locatedon the circuit board 426. The ceramic boss 440 located on each half unit404 electrically isolates the spinal member 406 to which it is connectedfrom both the end cap 13 and the end flange 403 with which it is incontact.

FIG. 9 shows the manner in which the tension rods 409 extending throughthru-holes 407 are electrically isolated from the end caps 13. As shownin FIG. 9 for the left-most end cap 13, a ceramic washer 444 surroundsthe head of each tension rod 409. The ceramic washer 444 electricallyisolates the end cap 13 from the tension rod 409. Because the sealestablished by the ceramic washer 444 is not hermetic, copper washers446 and 448 are also provided to ensure that such a hermetic seal isachieved between the tension rod and the end cap 13. The threaded end ofthe tension rods 409 terminate in the opposing end cap 13 and thethreaded ends are not electrically isolated from the end cap 13.

Since the sleeve 14 of the pressure vessel contacts the end caps 13 ofthe pressure vessel, sleeve 14 should preferably be formed from anon-conductive material. For example, sleeve 14 may be formed from athermally conductive ceramic, which is advantageous because of itsstrength. However, because such ceramics are often nominallyelectrically conductive they need to be provided with an oxide surfacein order serve as a dielectric. The surface finish of the oxide ispreferably polished to facilitate formation of a hermetic seal.

In some embodiments of the invention it may be advantageous if thesleeve 14 is formed from a metallic material such as stainless steel. Inthis case electrical continuity between the sleeve and the end caps 13of the pressure vessel may be broken by use of an electricallyinsulating ring that is inserted between one of the end caps 13 and thesleeve 14. An example of such a ring is shown in FIG. 11. In thisexample the insulating ring 6 is configured to have the same radialdimensions as the sleeve 14. The insulating ring 6 may be formed fromany appropriate material such as a ceramic. The opposing end faces ofthe ceramic ring 6 are preferably polished so that each end face forms aseal with either the end cap or tension sleeve 14.

Thermal Management

The pump sources 427 and zener diodes generate a significant amount ofheat that must dissipated to ensure that the temperature of the variouscomponents do not exceed their operational limits. This is aparticularly challenging problem because the pump sources 427 and zenerdiodes may generate several watts of power over a small area. Moreover,the thermal energy must be dissipated while simultaneously achievingelectrical isolation of these same components, two goals which areclearly somewhat at odds with one another. As detailed below, a numberof features of the optical amplifier module 400 enhance thermalmanagement so that the heat is adequately dissipated.

As previously mentioned, pump sources 427 are mounted on the pumpsupport bosses 403 a of the end flange 403. The heat from the pumpsources 427 is thereby conducted through the pump support bosses 403 ato the end flange 403, which has a relatively large mass so that itserves as an effective heat sink. The end flange 403 in turn conductsthe heat to the end caps 13 seen in FIG. 3.

The sidewalls 412 of the optical amplifier module 400 are made from athermally conductive material such as a metal, preferably aluminum.Since the sidewalls 412 have a relatively large surface area, they serveas a spreader that distributes the heat over its surface in a uniformmanner so that its local and overall temperature rises are kept to aminimum. The zener diodes are preferably situated as close to thesidewalls 412 as possible to so that the heat generated by the diodescan be readily conducted to the sidewalls 412.

For example, as best seen in FIG. 10, in one embodiment of the inventionthe zener diodes 484 are located on the bottom of the circuit board 426(i.e., the side of the circuit board opposite from that on which thepump sources 427 reside). Copper pads 480 are located on this bottomsurface, below each of the ceramic isolators 442 that isolates bolts 482that secure the circuit board 426 to the support surface 416. The zenerdiodes 484 are mounted on the copper pads 480, adjacent to the bolts482. The copper pads 480 serve as one of the electrical contacts foreach of the zener diodes 484, the other of which is denoted by referencenumeral 486. A portion of each copper pad 480 resides on the circuitboard support surface 416. The copper pads 480 contact the electricallyinsulating pad on which the circuit board 426 rests. The electricalinsulating pad is a relatively good thermal conductor and therebyconducts the heat generated by the zener diodes 484 from the copper pads480 to the circuit board support surface 416 of the optical amplifiermodule 400. In this way heat flows from the zener diodes 484, throughthe copper pads 480 and the electrical insulating pad, and into theoptical amplifier module 400. Once the heat has been distributed overthe sidewalls 412 of the module 400 the heat is directly conducted tothe stainless steel sleeve 14 that surrounds module 400.

The wide distribution of heat over the relatively large surface area ofthe end caps 13 and the tension sleeve 14 allows the heat to beeffectively conducted through the surrounding polyethylene sleeve 16,which is not a particularly good thermal conductor, to sea water.

1. An undersea optical repeater, comprising: a pressure vessel for usein an undersea environment, said pressure vessel including a pressurehousing and at least two cable receiving elements disposed on opposingends of the pressure housing for respectively receiving ends of opticalcables that each include an electrical conductor therein, said cablereceiving elements adapted to be in electrical contact with therespective electrical conductors in the optical cables; at least oneoptical amplifier located in the pressure vessel, said optical amplifierincluding at least one electrical component adapted to receiveelectrical power from the electrical conductors in the optical cables;and wherein said pressure vessel includes an electrically insulatingelement electrically isolating at least one of the cable receivingelements from the pressure housing.
 2. The undersea optical repeater ofclaim 1 wherein said electrically insulating element comprises a ceramicelement.
 3. The undersea optical repeater of claim 1 wherein saidpressure housing and said electrically insulating element arecylindrical in shape and are equal in diameter.
 4. The undersea opticalrepeater of claim 2 wherein said pressure housing and said electricallyinsulating element are cylindrical in shape and are equal in diameter.5. The undersea optical repeater of claim 1 wherein said pressurehousing is formed from a metallic material.
 6. The undersea opticalrepeater of claim 1 wherein said pressure vessel is a pressure vesseladapted for an undersea optical fiber cable joint.
 7. The underseaoptical repeater of claim 1 wherein said pressure vessel is a pressurevessel adapted for a universal cable joint for jointing optical cableshaving different configurations.
 8. The undersea optical repeater ofclaim 1 further comprising an optical amplifier module located withinthe pressure vessel for containing said at least one optical amplifier.9. The undersea optical repeater of claim 8 wherein said opticalamplifier module comprises: an internal housing having an outerdimension substantially equal to an outer dimension of an internal fibersplice housing of an undersea optical fiber cable joint, said internalhousing including: a pair of opposing end faces each having a retainingelement for retaining the internal housing within an outer housing ofsaid undersea optical fiber cable joint; a sidewall interconnecting saidopposing end faces and extending between said opposing end faces in alongitudinal direction, said sidewall including a receptacle portionhaving a plurality of thru-holes each being sized to receive a passiveoptical component employed in an optical amplifier; and at least onecircuit board on which reside electronics associated with the opticalamplifier.
 10. The undersea optical repeater of claim 9 furthercomprising at least one optical pump source in thermal contact with oneof the end faces.
 11. The undersea optical repeater of claim 10 whereinsaid end faces each include at least one inwardly extending boss, saidat least one optical pump source residing on one of the inwardlyextending bosses.
 12. The undersea optical repeater of claim 9 whereinsaid electronics associated with the optical amplifier includes at leastone voltage dropping element.
 13. The undersea optical repeater of claim12 wherein a first side of the circuit board resides on a surfaceextending through the sidewall and further comprising a thermallyconductive pad mounted to the first side of the circuit board andproviding a thermally conductive path between the voltage droppingelement and the sidewall.
 14. The undersea optical repeater of claim 13wherein the voltage dropping element is mounted to the thermallyconductive pad.
 15. The undersea optical repeater of claim 13 whereinsaid voltage dropping element is a zener diode.
 16. The undersea opticalrepeater of claim 9 wherein said plurality of thru-holes laterallyextend through said receptacle portion of the sidewall in thelongitudinal direction.
 17. The undersea optical repeater of claim 9wherein said internal housing has a generally cylindrical shape, saidreceptacle portion of the sidewall having a curvature that defines adiameter of the cylindrical shape.
 18. The undersea optical repeater ofclaim 9 further comprising an optical fiber storage area located withinsaid internal housing.
 19. The undersea optical repeater of claim 18wherein said optical fiber storage area includes at least one opticalfiber spool around which optical fiber can be wound.
 20. The underseaoptical repeater of claim 9 wherein said internal housing is formed froma pair of half units that each include one of the retaining elements.21. The undersea optical repeater of claim 20 wherein each circuit boardis located in a different one of the half units.
 22. The underseaoptical repeater of claim 9 wherein said sidewall includes a pair ofribbed members extending longitudinally from the receptacle portion ofthe sidewall, said ribbed members each having a tension rod thru-holeextending laterally therethrough in the longitudinal direction forsupporting a tension rod employed by the undersea optical fiber cablejoint.
 23. The undersea optical repeater of claim 9 wherein the outerdimension of the internal housing is less than about 15 cm×50 cm. 24.The undersea optical repeater of claim 9 wherein the outer dimension ofthe internal housing is about 7.5 cm×15 cm.